If you work hard and play by the rules, you will move up. That is the gist of the American dream. In Donald Trump’s view, however, hundreds of thousands of “Dreamers” who arrived as undocumented children were breaking the rules. Roughly two-thirds of Americans disagree, including virtually every business leader of note and many leading Republicans. If Congress fails to protect the Dreamers, President Trump can blame them. The buck never stops at Mr Trump’s desk.

He has given Capitol Hill six months to agree on what it has been unable to do in more than 30 years: pass an immigration reform bill. After that, most Dreamers will be at fate’s mercy. The odds that this Congress, which has had the least productive first eight months of any in US history, will do so are slim. No big reform is likely without White House support. In theory, Mr Trump is neutral on whether it should legalise the Dreamers, or kick them out of the country. In reality he is in favour of deportation. He just wants others to press the eject button.

The move is quintessential Trump on many levels. First, his reasoning is typically garbled. All of a sudden Mr Trump believes in constitutional limits to his power. Barack Obama offered a reprieve to the Dreamers by executive order, thus supposedly trampling on Congress’s turf. But that interpretation is by no means clear-cut. Other scholars say presidents have the right to interpret how to enforce the law. Mr Obama simply rolled out a “deferred action” on one type of illegal immigrant — children brought to the US by their parents, typically around the age of six.